Boeing Plans Further 787 System Flight Tests

Boeing today conducted a flight test on LN86, the aircraft being used for 787 tests, which the company says were unrelated to a fix for the aircraft’s lithium-ion batteries.

The aircraft, also known by its Boeing production designation as ZA272, originally was expected to make a test flight on March 30, but for unknown reasons this was cancelled. Boeing says the “flight is unrelated to the ongoing 787 battery certification testing. The battery certification demonstration flight will take place in the coming days.”

The airframer last flew ZA272 when it conducted a functional test flight on March 25.

The interim testing appears to be focused on verifying the functionality of specific systems that could play a key role in the upcoming battery demonstration flight, as well as other electrical systems unrelated to the battery modification. A revised power panel design was expected to be tested as part of the canceled March 30 flight from Paine Field at Boeing’s Everett, Wash., production facility.

The power panel has been the source of early in-service issues with the 787, as revealed by launch operator All Nippon Airways, which indicated the unit had been the cause of erroneous error messages on the engine indicating and crew alerting system during events in March, April and June 2012. Investigators found that a short in one of the power panel circuit boards caused the April event.

Power panel malfunctions also were behind a string of events in December that triggered error messages indicating failures of the aircraft’s starter generators. The first of these took place on Dec. 4, causing the crew of a United Airlines 787 to divert to Louis Armstrong New Orleans International Airport, while similar events struck another United 787 and a Qatar Airways aircraft on its delivery flight.

Issues with the power panel where soon overshadowed by the battery failures in January, which led to the grounding of the fleet later that month. April 1 represents the 76th day that the 787 fleet has been inactive.

Commenting on the power panel events in January, Boeing 787 VP and Chief Project Engineer Mike Sinnett said, “The event on United Airlines was a surprise to us. We’d only seen one thing that looked like that before, then we saw three more.”

When the United diversion took place on Dec. 4, Boeing was “in the middle of corrective action. We had a one-off manufacturing flaw that led to a generator channel (one of six) becoming inoperative. We’d only seen it once in 100,000 hours on the system. Then we had the similar event on the United airplane and two days later a similar one on Qatar. We realized all three of those boards came from the same 16 boards in one manufacturing lot,” Sinnett added.

Other systems understood to be targeted for testing include back-up standby instrument displays and the crew information system, a Honeywell-developed aircraft health monitoring feature that forms part of the 787’s central maintenance computer. The device interprets more than 100,000 system parameters and 30,000 fault conditions and transmits them via a real-time datalink to the ground.

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